The Resource Reservation Protocol (RSVP) is a transport layer protocol which allows resources to be reserved across a network. The resources are generally reserved for a flow. Typically, a sender of a request will send an RSVP reservation initiation, or PATH, message downstream to a receiver. The receiver will send an RSVP reservation response (RESV) message upstream towards the PATH originator of the request in response to the PATH message. Some hops in a path between the receiver and the sender is arranged to create and maintain a reservation state that is associated with the resources reserved for data packets which are to be sent from the sender.
In some systems, an integrated services MULTI-TSPEC object may communicate more than one traffic specification (TSPEC) request in the same RSVP setup message exchange. When more than one TSPEC request is communicated, each containing a separate bandwidth request, a recipient of the TSPEC request, e.g., a router along a path, may allocate an acceptable amount of bandwidth that is available with respect to the recipient, even if the recipient is unable to allocate a preferred, e.g., maximum desired, amount of bandwidth. That is, an acceptable amount of bandwidth that is less than a preferred amount of bandwidth may be reserved for a source or a sender when the source or the sender communicates more than one TSPEC request in the same RSVP setup message exchange. This results in an acceptable, but not optimal or preferred, reservation bandwidth between the source and a receiver.
A recipient that has established a reservation for less than a preferred amount of bandwidth for a source may determine, at some point after the reservation has been established, that the recipient may allocate more bandwidth to the source. In order for the source to take advantage of the additional bandwidth that is available, additional reservation exchanges, which typically involve trial and error, occur. Thus, obtaining additional bandwidth for use with respect to an existing reservation is generally inefficient.